Automated interleaved spectral imaging calibration

Abstract

An imaging spectrometric instrument is disclosed. This instrument can include an imaging detector and one or more calibration standards having different optical properties. Portions of one or more actuators can move the calibration standards between the imaging detector and a sample. This instrument can use the actuator(s) to acquire an image of a sample and measure light and dark reference calibration values in quick succession at a given wavelength, before the instrument is tuned to another wavelength.

1. A calibration standard assembly for an imaging spectrometric instrument that includes an imaging sensor based on a two-dimensional array of detector elements, comprising:
 a first calibration standard having a first set of optical properties, 
 a first actuator portion operatively connected to the first calibration standard and operative to move the first calibration standard in and out of a field of view of the imaging spectrometric instrument, 
 sequencing means including means for performing steps of each automatically acquiring an image using the image sensor, automatically moving the first calibration standard using the first actuator portion, and automatically acquiring calibration data from the first calibration standard using the image sensor for a first wavelength, wherein the sequencing means also includes means for repeating the steps of automatically acquiring an image using the image sensor, automatically moving the first calibration standard using the first actuator portion, and automatically acquiring calibration data from the first calibration standard using the image sensor for each of a plurality of further wavelengths in a range of instrument wavelengths to acquire a sequence including a plurality of images and a plurality of corresponding calibration data sets for detector elements in the two-dimensional array, and 
 means for correcting data for each of the images based on the calibration data acquired for the wavelength used to acquire that image to generate a calibrated hyperspectral sample image data set that includes corrected data for the images at the different wavelengths. 
 
     
     
       2. The apparatus of  claim 1  further including a second calibration standard having a second set of optical properties different from the first set of optical properties, and a second actuator portion operatively connected to the second calibration standard and operative to move the second calibration standard in and out of a field of view of the spectrometric instrument. 
     
     
       3. The apparatus of  claim 2  further including a support element to which the first and second calibration standards are connected, and wherein the first and second actuator portions are part of a common actuator that is operative to move the support element. 
     
     
       4. The apparatus of  claim 3  wherein the support element bears the first and second calibration standards at different radial positions about an axis of rotation and wherein the actuator is a motor operative to rotate the support element about the axis of rotation. 
     
     
       5. The apparatus of  claim 3  wherein the support element bears the first and second calibration standards at different linear positions along a first translation direction and wherein the actuator is a linear actuator operative to move the support element along the first translation direction. 
     
     
       6. The apparatus of  claim 3  wherein the support element further includes an opening and wherein the actuator is operative to move the opening into the field of view of the imaging spectrometric instrument. 
     
     
       7. The apparatus of  claim 3  further including a removable coupling mechanism between the support element and the actuator to allow for replacement of the support element with further, different support elements. 
     
     
       8. The apparatus of  claim 7  further including a machine-readable identifier on the support element, the first calibration standard, or the second calibration standard. 
     
     
       9. The apparatus of  claim 2  wherein the first calibration standard is a bright reference and wherein the second calibration standard is a dark reference. 
     
     
       10. The apparatus of  claim 1  wherein the first actuator portion is operative independent of any movement of a sample in the field of view of the imaging spectrometric instrument. 
     
     
       11. The apparatus of  claim 1  further including a further actuator portion operatively connected to a multi-sample holding element. 
     
     
       12. An imaging spectrometric instrument, comprising:
 an imaging detector, 
 a first calibration standard having a first set of optical properties, 
 a first actuator portion operatively connected to the first calibration standard and operative to move the first calibration standard between the imaging detector and a sample, 
 sequencing means including means for performing steps of a automatically acquiring an image using the imaging detector, automatically moving the first calibration standard using the first actuator portion, and automatically acquiring calibration data from the first calibration standard using the imaging detector for a first wavelength, wherein the sequencing means also includes means for repeating the steps of automatically acquiring an image using the image sensor, automatically moving the first calibration standard using the first actuator portion, and automatically acquiring calibration data from the first calibration standard using the image sensor for each of a plurality of further wavelengths in a range of instruments wavelengths, to acquire a sequence including a plurality of images and a plurality of corresponding calibration data sets for the imaging detector, and 
 means for correcting data for each of the images based on the calibration data acquired for the wavelength used to acquire that image to generate a calibrated hyperspectral sample image data set that includes corrected data for the images at the different wavelengths. 
 
     
     
       13. The apparatus of  claim 12  wherein the imaging detector is a detector that is sensitive to infrared wavelengths. 
     
     
       14. The apparatus of  claim 12  wherein the imaging detector is a detector that is sensitive to visible wavelengths. 
     
     
       15. The apparatus of  claim 12  wherein the imaging detector is a detector that is sensitive to ultraviolet wavelengths. 
     
     
       16. A method of acquiring a calibrated hyperspectral image data set for a sample using an imaging spectrometric instrument that includes an imaging sensor based on a two-dimensional array of detector elements and storage for the hyperspectral image data set, comprising:
 automatically acquiring a first image of a sample at a first wavelength using the two-dimensional array of detector elements, 
 automatically moving a first calibration standard between the sample and the imaging sensor of the instrument using an actuator, 
 automatically acquiring calibration data for the detector elements employed to acquire the first image from the first calibration standard after the step of moving the first calibration standard between the sample and the imaging sensor, 
 automatically moving the calibration standard out from between the sample and the imaging sensor of the instrument using the actuator, after the step of acquiring calibration data, 
 automatically adjusting an instrument acquisition wavelength from the first wavelength to a second wavelength after the steps of automatically acquiring calibration data and automatically acquiring a first image, 
 after the steps of automatically acquiring a first image and automatically acquiring calibration data, automatically repeating the steps of automatically acquiring an image, automatically moving a first calibration standard, and automatically acquiring calibration data from the first calibration standard, for at least the second wavelength in a range of instrument wavelengths to acquire a plurality of images and a plurality of corresponding calibration data sets for detector elements in the two-dimensional array, and 
 correcting data for each of the images based on the calibration data acquired for the wavelength used to acquire that image to generate a calibrated hyperspectral sample image data set that includes corrected data for the images at the different wavelengths, wherein the hyperspectral image data set is stored in the storage. 
 
     
     
       17. The method of  claim 16  further including an initial calibration step before the step of acquiring a first image of the sample. 
     
     
       18. The method of  claim 16  further including a further interleaved succession of steps of acquiring images and acquiring calibration data for the sample and wherein the step of generating generates a calibrated hyperspectral data set for the sample from the steps of acquiring a first image, acquiring calibration data, acquiring a second image, automatically repeating, and the further interleaved succession of steps. 
     
     
       19. The method of  claim 16  wherein the steps of automatically moving the standard employ a dark reference as the standard. 
     
     
       20. The method of  claim 16  wherein the steps of automatically moving the standard employ a bright reference as the standard. 
     
     
       21. The method of  claim 16  wherein the steps of moving, acquiring, and generating take place independent of any movement of the sample. 
     
     
       22. The method of  claim 16  further including the steps of:
 moving a second calibration standard between the sample and the imaging sensor of the instrument after the step of automatically acquiring calibration data for the detector elements employed to acquire the first image, 
 acquiring calibration data from the second calibration standard after the step of moving the second calibration standard between the sample and the imaging sensor, and 
 after the steps of automatically acquiring a first image and automatically acquiring calibration data for the detector elements, automatically repeating the steps of automatically moving a second calibration standard and automatically acquiring calibration data from the second calibration standard, for at least the second wavelength in the range of instrument wavelengths to acquire the plurality of images and the plurality of corresponding calibration data sets for detector elements in the two-dimensional array. 
 
     
     
       23. The method of  claim 22  wherein the method employs a dark reference as the first calibration standard and a bright reference as the second calibration standard. 
     
     
       24. The method of  claim 22  wherein the method employs an imaging detector that is sensitive to infrared wavelengths. 
     
     
       25. The method of  claim 22  wherein the method employs an imaging detector that is sensitive to ultraviolet wavelengths. 
     
     
       26. The method of  claim 22  wherein the method employs an imaging detector that is sensitive to visible wavelengths. 
     
     
       27. A calibration standard assembly for an imaging spectrometric instrument that includes two-dimensional image sensing means, comprising:
 first calibration means having a first set of optical properties, 
 means for moving the first calibration means in and out of a field of view of the imaging spectrometric instrument, 
 sequencing means including means for, a) automatically acquiring an image using the image sensing means, automatically moving the first calibration means using the means for moving, and automatically acquiring calibration data from the first calibration means using the image sensing means, for a first wavelength, wherein the sequencing means also includes means for repeating the steps of automatically acquiring an image using the image sensor, automatically moving the first calibration standard using the first actuator portion, and automatically acquiring calibration data from the first calibration standard using the image sensor for each of a plurality of further wavelengths in a range of instrument wavelengths to acquire a sequence including a plurality of images and a plurality of corresponding calibration data sets for detector elements in the two-dimensional array, and 
 means for correcting data for each of the images based on the calibration data acquired for the wavelength used to acquire that image to generate a calibrated hyperspectral sample image data set that includes corrected data for the images at the different wavelengths.